Group shared distributed reservation protocol

ABSTRACT

A method ( 400 ) for creating a group shared distributed reservation in a wireless network. The method comprises collecting information about the distributed reservation availabilities of devices in the wireless network (S 410 ); selecting a group of shared devices to be included in the group shared distributed reservation based on the collected information (S 420 ); sending a reservation request to each device in the group of shared devices (S 430 ); and updating the group of shared devices to include only devices that accept the reservation request (S 460 ), thereby creating a group shared distributed reservation of medium access time slots.

This application claims the benefit of U.S. Provisional Application No.61/084,071 filed on Jul. 28, 2008.

The invention generally relates to block transmission techniques.

A distributed reservation protocol (DRP), defined as part of thewireless media (WiMedia) medium access control (MAC) specification,provides a mechanism for concurrent communications between devicesconnected in a WiMedia based wireless network. To this end, devicesallocate time slots, also referred to as medium access slots (MAS),before transmitting data. The DRP allows defining a set of rules toestablish, modify, maintain, release, and terminate MAS unicast andmulticast reservations. A unicast reservation includes a reservationowner and a reservation target, while a multicast reservation consistsof a single reservation owner and multiple reservation targets. All thetargets have a multicast address and the reservation ownersimultaneously sends traffic to all its targets.

In some cases, data traffic sent from a source device to a destinationdevice passes through one or more intermediate links before the dataarrives at the destination device. For example, in a wireless network100 shown in FIG. 1, traffic from a source device 110-1 is sent over alink (hop) 120-12 to a forwarding device 110-2 and over a link 120-23 toa destination device 110-3. A multihop transmission is required when asource device cannot directly reach a destination device or when onlylow data rates are supported over a direct link between a source anddestination device.

For such multihop transmissions, the DRP reserves a MAS for each link,while restricting the size of data frames and the MASs that can servethe transmission. As a result, there is at least one idle period at theend of each MAS for each hop of a multihop communication. As illustratedin FIG. 2 a MAS 200-N (where N is an integer number) is reserved for thelink 120-12 and a MAS 200-(N+1) is reserved for the 120-23 link. Inaddition, there is an idle period 210 between the MASs 200-N and200-(N+1), as data frame transmissions do not cross boundaries of a MAS,i.e., a reservation block. The DRP governs that a data frame received atthe forwarding device 110-2 should wait for MAS 200-(N+1) to start priorto transmitting data to the destination device 110-3. This significantlyincreases the end-to-end latency between a source device and adestination device.

Therefore, it would be advantageous to provide a mechanism for reducingthe latency of multihop transmissions in WiMedia based wirelessnetworks.

Certain embodiments of the invention include a method for creating agroup shared distributed reservation in a wireless network. The methodcomprises collecting information about the distributed reservationavailabilities of devices in the wireless network; selecting a group ofshared devices to be included in the group shared distributedreservation based on the collected information; sending a reservationrequest to each device in the group of shared devices; and updating thegroup of shared devices to include only devices that accept thereservation request, thereby creating a group shared distributedreservation of medium access time slots.

Certain embodiments of the invention also include a method for mediumaccess control (MAC) layers forwarding in a wireless network. The methodcomprises collecting link quality information about each wireless linkbetween a source device and its neighbour devices; collectinginformation about the distributed reservation availabilities of theneighbour devices; selecting a group of devices to participate in theMAC layers forwarding based on the collected information; creating agroup shared distributed reservation of medium access time slots,wherein the group shared distributed reservation includes devicesselected to participate in the MAC layers forwarding.

Certain embodiments of the invention further include a device forming aframe structure of a group shared distributed reservation protocolinformation element (GSDRP-IE) for transmission over a wireless network,wherein the GSDRP-IE includes: an element ID field having a predefinedvalue indicating that the GSDRP-IE is an information element of a groupshared distributed reservation; a control field including a stream indexand a distributed reservation availability information element (IE)request; a plurality of address fields including addresses of devices towhich the GSDRP-IE is targeted; and a length field designating the sizeof the control field and addresses fields.

The subject matter that is regarded as the invention is particularlypointed out and distinctly claimed in the claims at the conclusion ofthe specification. The foregoing and other features and advantages ofthe invention will be apparent from the following detailed descriptiontaken in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of a wireless network.

FIG. 2 is a diagram illustrating MAS reservations for multihopcommunication.

FIG. 3 is a schematic diagram of a group shared DRP information elementconstrued in accordance with an embodiment of the invention.

FIG. 4 is a flowchart illustrating a reservation negotiation processimplemented in accordance with an embodiment of the invention.

FIG. 5 is a diagram illustrating the process of MAS reservations formultihop communication using GSDRP.

FIG. 6 is a diagram illustrating a fast MAC layers forwarding processperformed using the GSDRP.

FIG. 7 is a flowchart describing the fast MAC layers forwarding processimplemented in accordance with an embodiment of the invention.

It is important to note that the embodiments disclosed by the inventionare only examples of the many advantageous uses of the innovativeteachings herein. In general, statements made in the specification ofthe present application do not necessarily limit any of the variousclaimed inventions. Moreover, some statements may apply to someinventive features but not to others. In general, unless otherwiseindicated, singular elements may be in plural and vice versa with noloss of generality. In the drawings, like numerals refer to like partsthrough several views.

A group shared distributed reservation protocol (DRP) includinginformation elements and reservation rules are disclosed in accordancewith certain embodiments of the invention. The group shared DRP can beutilized to reduce the end-to-end latency in wireless networks and,particularly in WiMedia based wireless networks. More specifically, thegroup shared DRP disclosed herein can be adapted to reduce the latencyof multihop transmissions in WiMedia based wireless networks.

The cornerstone of the group shared DRP is an information element (IE)(hereinafter “GSDRP-IE”) construed in accordance with the principles ofthe invention. As shown in FIG. 3, a GRDRP-IE 300 includes an element IDfield 310 having a predefined value indicating that the GSDRP-IE 300 isan information element of the group shared DRP, a length field 320, acontrol field 330, a number of M device address fields (collectivelyreferred to as 340) to include the addresses of the devices to which theGSDRP-IE 300 is sent. The length field 320 specifies the size, i.e.,number of bytes of the control 330 and address 340 fields. The controlfield 330 holds control information which includes, but is not limitedto a stream index and a DRP availability IE request. The stream index isused to uniquely indicate the traffic flow that the GSDRP-IE 300 serves.The DRP availability information element (IE) request indicates whetheror not devices should reply with their DRP availability IEs. In oneembodiment of the invention, the value of the DRP availability IErequest may be one of the values listed in Table 1.

TABLE 1 Value (2 bits) Description 00 Does not request DRP AvailabilityIE 01 Request DRP Availability IEs from devices in address fields 340 10Request DRP Availability IEs from all neighbour devices 11 Reserved

FIG. 4 shows a non-limiting and exemplary flowchart 400 illustrating thereservation negotiation process implemented in accordance with anembodiment of the invention. The purpose of the negotiation process isto reserve a MAS for data transmissions between two devices. Twodifferent information elements may be utilized in this process: theGSDRP-IE (e.g., a GSDRP-IE 300) and a standard DRP-IE which is definedin current versions of the DRP specification. At S410, an initiatingdevice collects DRP availabilities of one or more devices to be includedin the group shared DRP reservation. To this end, a GSDRP-IE is sent tothe devices where the DRP availability IE request (in the control field330) is set to either one of the values “01” or “10”, depending onwhether the availability request is from devices designated in theaddresses field 340 or from neighbour devices of the initiating device.A device receiving an availability request responds back with its DRPavailability IE indicating whether or not the device can reserve a MASto the initiating device.

At S420, the initiating device selects a group of devices to be includedin the group shared DRP reservation based on the collected availabilityinformation. The addresses of the selected devices are designated in anewly created GSDRP-IE. At S430 the newly created GSDRP-IE together witha standard DRP-IE are sent to all devices in the group. The GSDRP-IE andDRP-IE include the same value for their individual stream indexsub-fields, which are part of the control fields of the IEs.

At S440, each device receiving the DRP-IE and GSDRP-IE checks if bothIEs are valid. The check may include if both IEs have the same streamindex value and if the GSDRP-IE includes the receiving device address.If both checks result in an affirmative answer, then at S450, thereceiving device responds with a DRP-IE indicating if the reservationrequest is rejected or accepted. If the reservation request does notconflict with other existing reservations, the receiving device grantsthe reservation; otherwise, the receiving device denies the reservation.Specifically, when a reservation is granted, the receiving deviceindicates the acceptance of the reservation by sending back a DRP-IEhaving the same reservation status as in the received DRP-IE. A rejectedreservation is indicated by specifying in the reservation status thatthe reservation has not been established.

If one of the checks performed at S440 results in a negative answer, atS445, the receiving device denies the reservation. At S460, all DRP-IEreplies sent from devices are received at the initiating device, and thegroup is updated to include only devices that accepted the reservationrequest.

It should be appreciated that by creating a group shared DRPreservation, it allows transmitting data between devices without anyidle periods and more data frames can be sent during a single MAS.Referring back to the example shown in FIG. 2, the invention can beutilized to reduce the latency by creating a shared group of DRPreservations including the forwarding and destination devices 110-2 and110-3 where the source device 110-1 is the initiating device. As shownin FIG. 5, three data frames can be sent during MASs 200-N and200-(N+1), where no idle periods are required between frametransmissions. In addition, a frame received at the forwarding device110-2 does not wait for start of the MAS 200-(N+1) for transmitting datato the destination device 110-3.

The negotiation process described above is only one process provided aspart of the process for performing DRP reservation for a group ofdevices as disclosed according to certain embodiments of the invention.Other processes may include, but are not limited to, modifying andterminating a group shared DRP reservation.

To terminate a group shared DRP reservation, the reservation owner(i.e., initiating device) removes or stops sending the DRP-IE and theGSDRP-IE to devices in the group. As a result, all devices in the groupstop sending their corresponding DRP-IEs.

In accordance with certain embodiments of the invention a standard DRPreservation and an existing group shared DRP reservation can bemodified. Specifically, a reservation owner of a unicast/multicast DRPreservation can modify the reservation to a group shared DRPreservation. This is performed by selecting devices to join an existingDRP reservation based on their availability. Then, a reservation ownersends a GSDRP-IE with the value of the stream index field the same asthat of the DRP-IE for the DRP reservation. The selected devices areincluded in the address fields (e.g., field 340) of the GSDRP-IE. Eachdevice receiving the GSDRP-IE and DRP-IE can accept or reject therequest to join an existing DRP reservation using the process describedin detail above.

A reservation owner can also modify a DRP reservation (i.e., a reservedMASs) by changing the group of devices assigned with the reservation.With this aim, the reservation owner first determines the devices to beincluded in the modified group. Then, the address fields (e.g., fields340) in the corresponding GSDRP-IE are modified to designate theaddresses of only devices in the new group. A device that is removedfrom the group stops sending a corresponding DRP-IE, no longerassociated with the established reservation. A device that is newlyadded into the GSDRP-IE joins the established reservation by setting anacceptance status when responding with its DRP-IE. An acceptance statusis sent only if the reservation does not conflict with other existingreservations; otherwise, the device rejects the established reservationby setting a reject status in the responding DRP-IE.

In accordance with another embodiment of the invention the group sharedDRP can be utilized to implement a fast MAC layers forwarding process.As illustrated in FIG. 6, this process allows forwarding devices in thegroup to forward a data frame one after another in a single MAS and alsoto transmit multiple data frames in the same MAS.

FIG. 7 shows an exemplary and non-limiting flowchart 700 describing thefast MAC layers forwarding process implemented in accordance with anembodiment of the invention.

At S710, a source device requests link quality information aboutwireless links with its neighbor devices. At S720, the source devicerequests its neighbors to send their DRP availability as describedabove. At S730, based on the link quality information and DRPavailability of devices, the source device selects a group of devices toparticipate in the fast MAC layer forwarding. At S740, a source deviceeither initializes a new group shared DRP reservation or modifies anexisting reservation between itself and its target device or by usingthe selected group of devices. When a reservation is established orsuccessfully modified, the reserved MAS can be used for the fast MAClayer's forwarding.

The group shared DRP reservation method and information elementsdescribed herein can be implemented in communication systems including,but not limited to, a UWB based wireless personal area networks (PANs),WiMedia based wireless networks, or any time division multiple access(TDMA) or super-frame based wireless networks.

The foregoing detailed description has set forth a few of the many formsthat the invention can take. It is intended that the foregoing detaileddescription be understood as an illustration of selected forms that theinvention can take and not as a limitation to the definition of theinvention. It is only the claims, including all equivalents that areintended to define the scope of this invention.

Most preferably, the principles of the invention are implemented as acombination of hardware, firmware and software. Moreover, the softwareis preferably implemented as an application program tangibly embodied ona program storage unit or computer readable medium. The applicationprogram may be uploaded to, and executed by, a machine comprising anysuitable architecture. Preferably, the machine is implemented on acomputer platform having hardware such as one or more central processingunits (“CPU”), a memory, and input/output interfaces. The computerplatform may also include an operating system and microinstruction code.The various processes and functions described herein may be either partof the microinstruction code or part of the application program, or anycombination thereof, which may be executed by a CPU, whether or not suchcomputer or processor is explicitly shown. In addition, various otherperipheral units may be connected to the computer platform such as anadditional data storage unit and a printing unit.

I claim:
 1. A method comprising: collecting information aboutdistributed reservation availabilities of devices in a wireless networkthat uses a medium access control (MAC) protocol; selecting a group ofshared devices to be included in a group shared distributed reservationbased on the collected information; sending a reservation request toeach device in the group of shared devices; updating the group of shareddevices to include only devices that accept the reservation request;allocating as a reservation block at least first and secondtime-contiguous medium access slots during each of which one of more ofthe shared devices in said group can transmit data in accordance with agroup shared distributed reservation protocol, the medium access slotsbeing as defined by the MAC protocol; and transmitting data frames inthe reservation block from a transmitting device to a receiving devicethrough at least one forwarding device in the group of shared devices,the transmitting being carried out for the data frames in successionwithout an idle period prior to the end of the at least firsttime-contiguous medium access slot of said reservation block and withoutwaiting for a start of the at least second time-contiguous medium accessslot at its boundary with the at least first time-contiguous mediumaccess slot.
 2. The method of claim 1, wherein collecting theinformation about distributed availabilities of devices comprisessending a group shared distributed reservation protocol informationelement (GSDRP-IE) to the devices in the network.
 3. The method of claim2, wherein the GSDRP-IE includes at least: an element ID field having apredefined value indicating that the GSDRP-IE is an information elementof a group shared distributed reservation, a control field including astream index and a distributed reservation availability informationelement (IE) request, a plurality of address fields including theaddresses of the devices to which the GSDRP-IE is sent, and a lengthfield designating the size of the GSDRP-IE.
 4. The method of claim 3,wherein selecting the group of shared devices comprises creating a newGSDRP-IE to include an address of each selected device.
 5. The method ofclaim 4, wherein sending the reservation request comprises sending thenew GSDRP-IE and a distributed reservation protocol information element(DRP-IE) to each device in the group shared devices.
 6. The method ofclaim 5, wherein each device receiving the GSDRP-IE and the DRP-IEperforms: checking if the new GSDRP-IE and the DRP-IE are valid; andresponding with a DRP-IE indicating whether the reservation request isrejected or accepted.
 7. The method of claim 1, further comprisingterminating the group shared distributed reservation.
 8. The method ofclaim 1, further comprising modifying the group shared distributedreservation.
 9. The method of claim 1, wherein the wireless network isat least a WiMedia based network.
 10. A non-transitory computer readablemedium having stored thereon computer executable code that when executedcauses a processor to perform a process of: collecting information aboutdistributed reservation availabilities of devices in a wireless networkthat uses a medium access control (MAC) protocol; selecting a group ofshared devices to be included in a group shared distributed reservationbased on the collected information; sending a reservation request toeach device in the group of shared devices; updating the group of shareddevices to include only devices that accept the reservation request,and; allocating as a reservation block at least first and secondtime-contiguous medium access slots during each of which one of more ofthe shared devices in said group can transmit data in accordance with agroup shared distributed reservation protocol, the medium access slotsbeing as defined by the MAC protocol; and transmitting data frames inthe reservation block from a transmitting device to a receiving devicethrough at least one forwarding device in the group of shared devices,the transmitting being carried out for the data frames in successionwithout an idle period prior to the end of the at least firsttime-contiguous medium access slot of said reservation block and withoutwaiting for a start of the at least second time-contiguous medium accessslot at its boundary with the at least first time-contiguous mediumaccess slot.
 11. A method for medium access control (MAC) layersforwarding in a wireless network that uses a medium access control (MAC)protocol, the method comprising: collecting link quality informationabout each wireless link between a source device and the source device'sneighbor devices; collecting information about distributed reservationavailabilities of the neighbor devices; selecting a group of devices toparticipate in the MAC layers forwarding based on the collected linkquality information and the distributed reservation availabilitiesinformation; and creating a group shared distributed reservation ofmedium access time slots, wherein the group shared distributedreservation includes the devices sharing a reservation block andselected to participate in the MAC layers forwarding, the reservationblock comprising at least first and second time-contiguous medium accesstime slots during each of which one of more of the devices in said groupcan transmit data in accordance with a group shared distributedreservation protocol, the medium access time slots being as defined bythe MAC protocol; wherein the MAC layers forwarding allows transmittinga plurality of data frames in the reservation block from the sourcedevice to a destination device through one or more forwarding devices,the transmitting being carried out for the data frames in successionwithout an idle period prior to the end of the at least firsttime-contiguous medium access time slot of said reservation block andwithout waiting for a start of the at least second time-contiguousmedium access time slot at its boundary with the at least firsttime-contiguous medium access time slot, wherein the source device, thedestination device, and the one or more forwarding devices are in thegroup shared distributed reservation.
 12. The method of claim 11,further comprising modifying an existing group shared distributedreservation to include the selected devices.
 13. A non-transitorycomputer readable medium having stored thereon computer executable codewhen executed causes a processor to perform a process of medium accesscontrol (MAC) layers forwarding in a wireless network that uses a mediumaccess control (MAC) protocol, the process comprising: collecting linkquality information about each wireless link between a source device andthe source device's neighbor devices; collecting information aboutdistributed reservation availabilities of the neighbor devices;selecting a group of devices to participate in the MAC layers forwardingbased on the collected link quality information and the distributedreservation availabilities information; and creating a group shareddistributed reservation of medium access time slots, wherein the groupshared distributed reservation includes the devices sharing areservation block and selected to participate in the MAC layersforwarding, the reservation block comprising at least first and secondtime-contiguous medium access time slots during each of which one ofmore of the devices in said group can transmit data in accordance with agroup shared distributed reservation protocol, the medium access timeslots being as defined by the MAC protocol, wherein the MAC layersforwarding allows transmitting a plurality of data frames in thereservation block from the source device to a destination device throughone or more forwarding devices, the transmitting being carried out forthe data frames in succession without an idle period prior to the end ofthe at least first time-contiguous medium access time slot of saidreservation block and without waiting for a start of the at least secondtime-contiguous medium access time slot at its boundary with the atleast first time-contiguous medium access time slot, wherein the sourcedevice, the destination device, and the one or more forwarding devicesare in the group shared distributed reservation.
 14. The method asdefined in claim 1, wherein the method further comprises: forming aframe structure of a group shared distributed reservation protocolinformation element (GSDRP-IE) for transmission over a wireless network,wherein the GSDRP-IE includes: an element ID field having a predefinedvalue indicating that the GSDRP-IE is an information element of a groupshared distributed reservation; a control field including a stream indexand a distributed reservation availability information element (IE)request; a plurality of address fields including addresses of devices towhich the GSDRP-IE is targeted; and a length field designating the sizeof the control field and addresses fields, wherein the distributedreservation availability information element (IE) request indicateswhether or not the devices to which the GSDRP-IE is targeted shouldreply with their own distributed reservation availability informationelements.
 15. The method of claim 1 wherein at least one of the dataframes is transmitted from the transmitting device through theforwarding device to the receiving device within a single one of themedium access slots.
 16. The method of claim 15 wherein the receivingdevice is a destination device.
 17. The method of claim 1 wherein afirst portion of at least one of the data frames is transmitted from atleast one of a) the transmitting device and b) the forwarding deviceduring the first medium access slot and a second portion of that dataframe is transmitted from said at least one of a) the transmittingdevice and b) the forwarding device during the second medium accessslot.
 18. The non-transitory computer readable medium of claim 10wherein the group shared distributed reservation protocol enables dataframes to be transmitted from the transmitting device through theforwarding device to the receiving device within a single one of themedium access slots.
 19. The non-transitory computer readable medium ofclaim 18 wherein the receiving device is a destination device.
 20. Thenon-transitory computer readable medium of claim 10 wherein the groupshared distributed reservation protocol enables a first portion of atleast one of the data frames to be transmitted from at least one of a)the transmitting device and b) the forwarding device during the firstmedium access slot and enables a second portion of that data frame to betransmitted from said at least one of a) the transmitting device and b)the forwarding device during the second medium access slot.